Multidrug resistance pattern of bacterial agents isolated from patient with chronic sinusitis

Background: Treatment of chronic sinusitis is complicated due to increase of antibiotic-resistant bacteria. The aim of this study was to determine the multidrug resistance (MDR) pattern of the bacteria causing chronic sinusitis in north of Iran. Methods: This cross-sectional study was carried out on patients with chronic sinusitis. Bacterial susceptibility to antimicrobial agents was determined according to the CLSI 2013 standards. Double-disk synergy (DDS) test was performed for the detection of extended-spectrum beta-lactamase (ESBL) producing bacteria; also methicillin-resistant Staphylococcus (MRSA) strains were identified by MRSA screen agar. The MDR isolates were defined as resistant to 3 or more antibiotics. Data were analyzed using SPSS 17 software. Descriptive statistics was used to describe the features of the data in this study. Results: The rate of ESBL-producing bacteria was 28.75-37.03% among enterobacteriaceae and the rate of MRSA was 42.75%-60% among Staphylococcus strains. The most detectable rate of the MDR bacterial isolates was Gram-negative bacteria 39 (76.47%) and Enterobacter spp. 19(70.37%) was the most multidrug resistant isolate among Gram negative bacteria. Also 36 (73.46%) of the gram positive bacterial isolated were multidrug resistance and Staphylococcus aureus 9(90%) was the most MDR among Gram positive bacteria. Conclusion: Antimicrobial resistance is increasing in chronic bacterial sinusitis. The emergence of MRSA and ESBL bacteria causing chronic sinusitis is increasing.

T reatment of chronic sinusitis, as one of the more prevalent chronic illnesses is complicated due to increase of antibiotic-resistant bacteria (1,2). Recent reports have shown the emergence of antibiotic resistance bacteria in sinusitis and the increasing rate of multidrug resistance (MDR) enterobacteriaceae causing chronic sinusitis (3)(4)(5). Extendedspectrum beta-lactamases (ESBLs) and methicillin-resistant Staphylococcus strains (MRSA) represent a major threat among MDR bacterial isolates (6). There are limited reports regarding the prevalence of MRSA in the setting of chronic sinusitis (7). Treatment of chronic sinus infection associated with the recovery of MRSA is challenging. It is important to provide coverage against these organisms as well as against other potential aerobic and anaerobic bacteria (8)(9)(10) anaerobic bacteria and Staphylococcus aureus are more considerable bacteria in chronic sinusitis. Penicillin group, amoxicillin or amoxicillin-clavulanate are effective against bacteria causing sinusitis. There is increasing rate of MDR bacteria among respiratory pathogens, including pneumococci and H. influenzae. Resistance rates vary regionally (11,12).
Empiric antibiotic therapy is often used for sinusitis, on the other hand, the emergence of antibiotic resistance has increased the failure rate of this approach (13). The epidemiology of bacteria causing chronic sinusitis in European and American countries differs from Iran and in these countries people routinely vaccinate Hemophilus influenzae and pneumococcus. In our knowledge, not only there are limited data on common pathogens associated with sinusitis in Iranian patients, but also no comprehensive information exists on antimicrobial susceptibility to common antibiotics used for treating sinusitis. (14)(15)(16). In view of the increased resistance to antibiotics in several upper airway bacteria, the aim of this study was to determine the multidrug resistance(MDR) pattern of the bacteria causing chronic sinusitis in north of Iran.

Methods
This cross-sectional study was carried out on 100 patients with chronic sinusitis. The endoscopy method was used for bacterial sampling. The standard microbiological procedures were performed for the identification of the bacteria causing chronic sinusitis (17,18). Bacterial susceptibility to antimicrobial agents was determined by the Kirby-Bauer method according to the CLSI 2013 standards. Inoculums were diluted to final concentration (5*10 5 CFU/ ml) and inoculated into Mueller-Hinton agar (19). ESBL-producing enterobacteriaceae was detected using the double-disk synergy (DDS) test. ESBL presence was assayed using the following antibiotic disks (MAST, UK): ceftazidime/ clavulanic acid (30/10 μg) cefotaxime (30 μg), cefotaxime/ clavulanic acid (30/10 μg) and ceftazidime (30 μg). Escherichia coli ATCC 25922 strain served as positive control.

Discussion
Our results showed the increased role of MRSA and ESBL-producing bacteria in chronic sinusitis. Total of 20(47.61%) of Staphylococcus strains were MRSA and 17(33.33%) of enterobacteriaceae isolates were ESBLproducing bacteria. Increasing MRSA strains is a major problem in the hospital and community settings (23). We found that S. aureus has very high rate of antibiotic resistance. For example we reported 60% MRSA and 20% vancomycin-resistant S. aureus. Manarey identified 9.22% incidence of MRSA-causing chronic sinusitis (24). Brook (25,26). All isolates were susceptible to vancomycin in Dibah et al.'s research (26). Overall, the data illustrated that a significant increase occurred in the rate of MRSA in patients with chronic sinusitis. Outpatient intravenous antibiotics may be an effective therapy for the treatment of MRSA sinusitis (27). Community-acquired MRSA sinusitis can be treated on an outpatient basis with culture-directed oral antibiotics (28).
The rate of ESBL-producing bacteria was 28.75-37.03% among enterobacteriaceae in our study. Studies on patients infected by ESBL producing enterobacteriaceae have been shown to share several common factors. The presence of these risk factors should alert the attending physician to the possibility of an ESBL-related infection: Device related (arterial catheters; central venous catheters; urinary tract catheters; gastrostomy or jejunostomy tube; umbilical catheters), surgical related, antibiotic exposure (3rd generation cephalosporins (especially ceftazidime); fluoroquinolones; trimetroprim-sulfamethoxazole), previous nursing home residence, prolonged duration of hospital or ICU longer stay is associated with more severe underlying diseases, with invasive procedures and with antibiotic administration and severity of illness (22,(29)(30)(31)(32). Infections with ESBL-producing organisms are usually hospitalacquired. In our study, none of the patients had nosocomial infections and it seems only probable risk factor for the spread of ESBL bacteria was indiscriminate use of antibiotics such as amoxicillin, cefixime, azithromycin, ciprofloxacin, cotrimoxazole and so on. Many surveillance studies performed in Europe and other geographical regions showed an increased prevalence and dispersion of ESBL producing isolates (6). Similar to our findings, Rezai et al. reported 30.5% ESBL-producing E.coli (33). On one hand Akyar in Turkey found 12% ESBL-producing E.coli and Klebsiella pneumonia (34). Also, Heffernan in New Zealand, estimated species distribution among the ESBLenterobacteriaceae in 2012, the survey reported: 61.7% E. coli, 33.5% Klebsiella species and 2.8% Enterobacter species (35). Carbapenems such as imipenem or meropenem have been shown to be associated with the lowest mortality of any drug class when used against infections with ESBLproducing organisms (36).
The most detectable rate of MDR bacteria isolated were Gram negative bacteria 39(76.47%) and Enterobacter spp. was the most MDR isolates, also the antibiotic susceptibility test showed that 36 (73.46%) of the Gram positive isolates were MDR and Staphylococcus aureus 9(90%) was the most multidrug resistant among Gram positive bacteria. We found high prevalence of MDR bacteria among enterobacteriaceae family in our study, especially all  (33,37). We reported the sensitivity to antibiotics only in 9% of cases to 8-10 antibiotics and the total number of 76% microbial species was resistant to at least three antibiotic discs. In our study, we reported that resistance to cephalosporins such as cefuroxime, cefazolin, ceftazidime and ceftriaxone among enterobacteriaceae family was in average level similar to other studies (30,(38)(39)(40). Antibiotic choices in the treatment of chronic sinusitis should be guided by sinus cultures whenever possible, and the use of broader single antibiotic agent should be considered with or without the addition of anaerobic coverage antibiotics (41). Antimicrobial resistance is increasing in bacteria causing chronic sinusitis especially to beta-lactam antibiotics among Gram positive bacteria in our study. The emergence of MRSA and ESBL bacteria causing chronic sinusitis is increasing. In addition, this resistance affects the efficiency of different generations of cephalosporins in the treatment of chronic sinusitis.